Apparatus for melting metals



Oct. 25, 1932. 1.; R. ZIFFERER APPARATUS Funk. MELTING METALS Original Filed April 17, 1930 coal, so that the pyrite particles are of sub-' stantial size and readily find their way to the hearth through the pieces of metal placed thereon. Excessive sulphur is harmful in any cast iron, but it is particularly so in malleable cast iron, as it seriously affects complete graphitization in the annealing process with the result that ductility is decreased, machining is rendered difficult and the reliability of the casting is impaired.

Fluid fuels are much more expensive than coal. Oil is the cheapest fluid fuel and is sometimes used, notwithstanding its higher cost. In addition to its relatively high cost, oil possesses serious technical disadvantages. It causes high oxidation losses and excessive carbon losses from the metal, particularly when the latter is in the molten state. These advantages are substantially absent where heating temperatures below the melting point of cast iron are produced by means of a reducing flame. For heating cast iron to a pouring temperature, oil requiresan excess of air which results in the oxidation of the metal and the high carbon losses referred to. One outstanding virtue of oil, as a heating medium, is that it has no appreciable tendency to increase the sulphur content.

In accordance with the present invention, an apparatus is employed wherein the initial part of the heating is effected by means of oil, while the later heating is effected by means of coal. The change over from oil to coal may suitably be made at or about the time when the metal is melted wholly or in part. By the use of such an apparatus substantially all the difliculties and disadvantages inherent in the use of either heating medium alone are avoided. The oil is used in the initial part of the heating so as to provide a reducing atmosphere within the furnace, which, in turn, reduces the tendency for oxidation of iron and the subsequent loss of silicon, manganese and carbon to a minimum. The oxidation of iron is much more sensitive to furnace atmospheres while the metal is in a solid state or partially melted state, as the density of the mass while the iron is solid or partially so prevents the migration of carbon to the surface, allowing any free oxygen present to attack the iron directly to form iron oxide, which later in the melt reacts to reduce the carbon, silicon and manganese, and the last traces of such oxides remain in the melted metal to cause casting difiiculties. In addition to keeping the oxidation of iron and other elements to a minimum, as indicated above, this invention also prevents increase of sulphur content and by its use there is no appreciable ash or solid residue as in the case of pulverized coal.

IVhen the change over to powdered coal is made, it is possible to completely consume the coal owing to the high temperature of the furnace. Ash and non-combustible portions of fuel fall upon the slag on the surface of the molten metal and do not contaminate the same. At this stage of the melting cycle, by the use of pulverized coal, it is also possible to maintain a reducing or neutral atmosphere together with high temperatures, which is not possible while using oil as a fuel. This prevents high carbon loss and makes possible a more eflicient and economical melt-- ing mixture.

In order to more completely illustrate the invention, a more minute description of a specific example in which twenty tons of H011 are melted in a furnace of suitable size for that quantity is given below. The sprue and/or scrap iron, together with pig iron to form a desired charge, is placed upon the,

hearth 11 and the furnace roof replaced. It

may be noted that, owing to the fact that.

the present method does not add to the sulphur content of the melt, somewhat increased. quantities of h1gh sulphur iron may be employed in the charge. The blower 25 is started so as to supply the volumetric air for the combustion of the oil which is introduced by the nozzle 29 together with atomizing air supplied by the pipe 31. The volumetric air is controlled by partially opening or closing a shutter type damper 28 on the intake side of the blower which runs at constant speed. During the first hour or fifty minutes or so, a slightlylesser amount of oil is consumed the motor 20 is started to feeda supply of pulverized coal to the nozzles 26 together with the air from the blower 25. high temperature of the furnace, the coal con- Owing to the sumption is highly efiicient. This heating is continued for perhaps another three hours, or through such time as is sufficient to raise the temperature of the molten metal to a degree suitable for pouring.

Although the invention has been disclosed in connection withthe details of a specific embodiment thereof, it must be understood that, such details are not intended to be limitative of the invention except in so far as set forth in the accompanying claims.

IVhat is claimed is:

1. In combination, a reverberatory furnace comprising a hearth, a nozzle adapted for the injection of material thereinto, means for supplying air to the nozzle, a conduit adapted to supply finely divided solid fuel to the same nozzle, and means adapted to inject fluid fuel into the furnace at a point adjacent the nozzle aforesaid.

2. In combination, a reverberatory furnace comprising a hearth, a nozzle adapted for the injection of material thereinto, a blower for supplying air to'the nozzle, means for supplying finely divided solid fuel to the blower and thereby to the nozzle, a second nozzle adjacent the first nozzle, a valve controlled conduit adapted to supply oil thereto, and a valve controlled conduit adapted to supply atomizing airthereto.

3. In combination, a reverberatory furnace having a hearth, a pair of nozzles pointed to project two unidirectional streams of material over the hearth, means for supplying to one nozzle a regulable mixture of air and finely divided solid fuel, and means for supplying to the other nozzle a regulable mix-.

ture of air and liquid fuel.

4. In combination, a reverberatory furnace having a hearth, means for selectively projecting over the hearth two unidirectional streams of material, one of air and finely divided solid fuel and the other of air and liquid fuel, and means by which to regulate the mixtures comprised in each of such streams.

MABEL C. ZIFFERER, I HARRY E. CHAMPION, H. NELSON ALBRIGHT, Eweoutors of the Estate of Lothaz- R. Zfierer,

Deceased. 

